HELIOSCOPE
Etymology
Noun
helioscope (plural helioscopes)
(astronomy) An apparatus for viewing the sun without harming the eye, by means of blackened glass or mirrors that reflect only a part of the light.
Source: Wiktionary
He"li*o*scope, n. Etym: [Helio- + -scope: cf. F. hélioscope.]
(Astron.)
Definition: A telescope or instrument for viewing the sun without injury to
the eyes, as through colored glasses, or with mirrors which reflect
but a small portion of light.
– He`li*o*scop`ic, a.
Source: Webster’s Unabridged Dictionary 1913 Edition